Method and system of monitoring electrolyte levels and composition using capacitance or induction

ABSTRACT

Methods and systems for monitoring fluid levels and electrolyte levels used in a dialysis machine. A receptacle, configured to receive a container, comprises a plurality of curved side panels and a base to form a cylindrical shaped cavity for receiving a container. Each panel includes a conductive material on its inner surface and, optionally, a shielding on its outer surface. An electronics component housed within, or near, the receptacle drives the capacitive process and interprets generated data to determine fluid levels and compositions. An alternate receptacle includes one or two coils wrapped about the container and uses induction to determine fluid level.

CROSS-REFERENCE

The present application is a continuation application of U.S. patentapplication Ser. No. 15/988,214, entitled “Method and System ofMonitoring Electrolyte Levels and Composition Using Capacitance orInduction” and filed on May 24, 2018, and issued as U.S. Pat. No.10,613,048 on Apr. 7, 2020, which is a continuation application of U.S.patent application Ser. No. 14/924,134, of the same title, filed on Oct.27, 2015, and issued as U.S. Pat. No. 10,006,878 on Jun. 26, 2018, whichis a continuation application of U.S. patent application Ser. No.13/725,178, of the same title, filed on Dec. 21, 2012, and issued asU.S. Pat. No. 9,201,036 on Dec. 1, 2015.

FIELD

The present specification relates generally to fluid monitoring indialysis systems. More particularly, the present specification relatesto methods and systems using capacitance to monitor dialysis electrolytefluid levels and composition.

BACKGROUND

Blood purification systems, which are used for conducting hemodialysis,hemodiafiltration or hemofiltration, involve the extracorporealcirculation of blood through an exchanger having a semi permeablemembrane. Such systems further include a hydraulic system forcirculating blood and a hydraulic system for circulating replacementfluid or dialysate comprising the certain blood electrolytes inconcentrations close to those of the blood of a healthy subject.Standard dialysis treatment comprises two phases, namely, (a) dialysis,in which toxic substances and scoriae (normally small molecules) passthrough the semi-permeable membrane from the blood to the dialysisliquid, and (b) ultrafiltration, in which a pressure difference betweenthe blood circuit and the dialysate circuit, more precisely a reducedpressure in the latter circuit, causes the blood content of water to bereduced by a predetermined amount.

During dialysis treatment, the dialysate is stored locally for infusioninto the treatment process as needed. A standard cylindrical containeris filled with various compositions and non-sterile or sterile water toproduce the electrolyte or infusate. A tube is placed within the mixturefor drawing the electrolyte into the filtering components of thedialysis machine. In order to properly perform the dialysis procedure,the amount and composition of the electrolyte must be continuously andaccurately monitored.

One method of monitoring involves using an optical camera and a weightscale to monitor the composition and amount, respectively, of theelectrolyte. For example, U.S. patent application Ser. No. 13/023,490,entitled “Portable Dialysis Machine”, filed on Feb. 8, 2011 and assignedto the applicant of the present invention, describes how “desiredquantities of an infusate solution can be added to the dialysis fluid.Infusate is a solution containing minerals and/or glucose that helpreplenish minerals like potassium and calcium in the dialysate fluid atlevels after undesired removal by the sorbent. A peristaltic pump isprovided to pump the desired amount of infusate solution to [a]container. A camera may optionally be provided to monitor the changingliquid level of the infusate solution as a safety check warning ofinfusate flow failure . . . . The container is also equipped with ascale for keeping track of the weight, and therefore volume, of thefluid in the container.” U.S. patent application Ser. No. 13/023,490 isincorporated herein by reference in its entirety.

Although the use of a camera and scale provides a mechanism formonitoring the level and composition of electrolyte, an improved,non-invasive system to monitor electrolytes, while requiring fewercomponents and being more inexpensive and easier to commerciallyimplement, is still needed.

SUMMARY

The present specification is directed toward a system for monitoringelectrolyte of a dialysis machine, comprising: a cylindrical shapedreceptacle configured to receive a container, wherein said receptaclecomprises an even numbered plurality of curved panels arranged in asubstantially circular or semi-circular pattern atop a base, whereineach of said panels comprises a concave inner surface facing saidcontainer and an outer surface opposite said inner surface and whereineach of said panels includes a conductive material on its inner surfaceand a shielding material on its outer surface. Each panel iselectrically isolated from each other panel. A container houses theelectrolytes and is configured to fit within the receptacle. Electronicsare housed within the receptacle and are adapted to drive a capacitiveprocess to generate characteristic data of the electrolytes. Theelectronics interpret the data to provide a user with informationregarding the fluid level and composition of the electrolytes.

In one embodiment, the electronics are housed in the base of thereceptacle. In another embodiment, the electronics are housed in acompartment positioned on an external side of the receptacle.

In one embodiment, the conductive material is copper. In one embodiment,the shielding material is also copper.

In one embodiment, each panel further comprises two side surfaces normalto the outer surface, wherein each side surface includes a fin extendingoutwardly from and extending along the entire vertical length of eachside surface such that two opposing fins are in physical contact at saidbase of said receptacle but do not touch at the top edge of thereceptacle.

The present specification is also directed toward a method of monitoringelectrolytes used in a dialysis machine by providing a receptacle systemadapted to inductively measure electrolytes. The receptacle systemincludes a substantially cylindrically shaped receptacle configured toreceive a container, wherein said receptacle comprises a plurality ofcurved panels arranged in a circular pattern atop a base. Each of thepanels comprises a curved inner surface facing the container and anouter surface opposite the inner surface. Each of the panels alsoincludes a metallic material on its inner surface and a shieldingmaterial on its outer surface. Preferably, each panel is electricallyisolated from the other panels. In one embodiment, the receptacle housesthe electronics and is configured to receive an electrolyte containerwhere the electrolyte container is operatively connected to a fluidcircuit of the dialysis machine. The method further includes 1)performing a dialysis treatment on a patient using the machine andoperating the electronics to generate an alternating current (AC)excitation of the conductive material on the inner surface of the atleast one panel, 2) measuring the coupled response in the conductivematerial on the inner surface of the opposing panel to determinecapacitance, and 3) comparing the measured capacitance with thepredetermined capacitance of known liquids to determine the fluid leveland composition of the electrolyte.

The present specification is also directed toward a system formonitoring electrolytes in a fluid used in a dialysis procedure,comprising: a cylindrical shaped receptacle configured to receive acontainer for holding the electrolytes, wherein said receptaclecomprises a base from which extends a pair of intertwined, mutuallyshielded conductive coils that wrap around said container andelectronics housed within the receptacle, wherein, said electronicsdrive a mutual inductive process to generate characteristic data of theelectrolytes and wherein said electronics interpret said data to providea user with information regarding the fluid level of the electrolytes.

In one embodiment, the system for monitoring the electrolytes of adialysis machine further comprises at least one temperature sensor tomeasure the temperature of said electrolytes.

In one embodiment, the electronics are housed in the base of thereceptacle. In another embodiment, the electronics are housed in acompartment positioned on an external side of the receptacle.

In one embodiment, the conductive coils are made of copper.

The present specification also discloses a method of monitoringelectrolytes in a fluid for use in a dialysis machine by providing anelectrolyte container and receptacle system. The receptacle systemcomprises a receptacle configured to receive a container, wherein saidreceptacle comprises a base from which extends a pair of intertwined,mutually shielded conductive coils that wrap around the container,electronics, and a container for holding the electrolytes in fluid andconfigured to fit within the receptacle. The method operatively connectssaid electrolyte container and receptacle system to the dialysatecircuit of a dialysis machine, performs a dialysis treatment on apatient using the dialysis machine, operates the electronics to generatean alternating current (AC) excitation of one of said pair of conductivecoils, and measures the coupled response in the other coil on theopposing side of the container to determine mutual inductance. Themeasured inductance is then compared with the predetermined inductanceof known liquids to determine the fluid level of the electrolytes.

In one embodiment, the electrolyte container and receptacle systemfurther includes at least one temperature sensor. The method ofmonitoring electrolytes further comprises the steps of: measuring thetemperature of the electrolytes using said at least one temperaturesensor, applying a function to said temperature measurement and saidmeasured inductance to yield an output, and comparing said output tocomparable data for compositions of known liquids to determine thecomposition of said electrolyte.

The present specification is also directed toward a system formonitoring electrolytes of a dialysis machine, comprising: acylindrically shaped receptacle configured to receive a container,wherein said receptacle comprises a base from which extends a singleshielded conductive coil that wraps around said container, electronicshoused within the receptacle, and a container for holding electrolytesand configured to fit within said receptacles, where the electronicsdrive a single inductive process to generate characteristic data of theelectrolytes and wherein the electronics interpret the data to provide auser with information regarding the fluid level of the electrolytes.

In one embodiment, the system for monitoring the electrolytes used in adialysis machine further comprises at least one temperature sensor tomeasure the temperature of said electrolytes.

In one embodiment, the electronics are housed in said base of saidreceptacle. In another embodiment, the electronics are housed in acompartment positioned on an external side of the receptacle.

In one embodiment, the conductive coil is composed of copper.

The present specification is also directed toward a method of monitoringelectrolytes in a fluid used in one or more fluid circuits of a dialysismachine. The method comprising the steps of: placing a container in areceptacle, wherein said receptacle comprises a base from which extendsa single shielded conductive coil that wraps around the container andwherein the receptacle houses electronics, operatively connecting saidelectrolyte container and receptacle system to the dialysate circuit ofa dialysis machine, performing dialysis treatment on a patient usingsaid machine, operating said electronics to generate an alternatingcurrent (AC) excitation of said single conductive coil, measuring thecoupled response in the coil on the opposing side of the container todetermine single inductance, and comparing the measured inductance withthe predetermined inductance of known liquids to determine the fluidlevel of the electrolyte.

In one embodiment, the electrolyte container and receptacle systemfurther includes at least one temperature sensor. The method ofmonitoring the electrolytes further comprises the steps of: measuringthe temperature of said electrolytes using said at least one temperaturesensor, combining said temperature measurement with said measuredinductance, and comparing said combined data to temperature andinductance data for compositions of known liquids to determine thecomposition of said electrolyte.

The present specification is also directed toward a system formonitoring electrolytes in a fluid used in a dialysis machine,comprising: a receptacle configured to receive a container, wherein saidreceptacle comprises an even numbered plurality of panels arranged in apattern atop a base, wherein each of said panels comprises a concaveinner surface facing said container and an outer surface opposite saidinner surface, wherein each of said panels has a conductive material onits inner surface, and wherein each panel is electrically isolated fromeach other panel; and a circuit in electrical communication with atleast one of said plurality of panels; wherein said circuit isconfigured to drive a capacitive process to generate characteristic dataof said electrolytes.

In one embodiment, the receptacle in combination with said plurality ofpanels forms a structure defining a cavity that is substantiallycylindrical.

In one embodiment, the circuit is housed within the base of thereceptacle. In another embodiment, the circuit is housed in acompartment located external to said receptacle.

In one embodiment, the conductive material is copper. In one embodiment,the outer surface comprises a shielding material wherein the shieldingmaterial is copper.

In one embodiment, each panel further comprises two side surfaces normalto said outer surface wherein each side surface includes a fin extendingoutwardly from, and along, the entire vertical length of each sidesurface. In one embodiment, the receptacle comprises four panels whereinthe fins of adjacent panels are in physical contact at said base of saidreceptacle but do not touch at the top edge of said receptacle.

In one embodiment, the system for monitoring electrolytes furthercomprises a container for holding electrolytes and configured to snuglyfit within said receptacle.

In one embodiment, the circuit drives the capacitive process to generatecharacteristic data of said electrolytes by generating an alternatingcurrent in a form of a stimulation wave and transmitting such wave to atleast one of said plurality of panels and receiving a responsive wavegenerated by a panel opposing said one of said plurality of panels. Inone embodiment, the circuit drives the capacitive process to generatecharacteristic data of said electrolytes by further comparing dataderived from said responsive wave to predetermined capacitance data forliquids with known levels and electrolyte compositions and determining afluid level and a composition of the electrolytes in said fluid based onthe data derived from the responsive wave and predetermined capacitancedata.

In one embodiment, the receptacle further comprises a temperature sensorwherein the circuit is configured to receive data indicative of atemperature from the temperature sensor, apply a function of said dataand data generated from said capacitive process to generate an output,and compare said output to data derived from compositions of liquidshaving known levels of electrolytes and temperatures, and, based on saidcomparison, determine a composition of said electrolytes in said fluid.

The present specification is also directed toward a method of monitoringa fluid having a fluid level and electrolytes in a dialysis system, saidmethod comprising the steps of: providing a receptacle configured toreceive a container, wherein said receptacle comprises a base, a firstpanel attached to said base, a second panel attached to said base, andcircuitry in electrical communication with said first panel and saidsecond panel, wherein each of said first and second panels comprises acurved inner surface facing said container, wherein each of said firstand second panels includes a conductive material on its inner surface,and wherein each panel is electrically isolated from each other panel;filling the container with water and electrolytes; operativelyconnecting a fluid flow path from a dialysate circuit in the dialysissystem to said container; performing a dialysis treatment on a patientusing said dialysate circuit; and, operating said circuit to generate anelectrical excitation of the conductive material on the inner surface ofthe first panel; measuring a capacitance arising from the electricalexcitation of the conductive material on the inner surface of the firstpanel in the second panel; determine the fluid level and composition ofthe electrolytes based on said measured capacitance.

In one embodiment, the electrolytes are at least one of potassium,magnesium, or calcium.

In one embodiment, the circuitry comprises a processor and memorystoring programmatic instructions that, when executed, generates analternating current in a form of a stimulation wave and transmits suchwave to the first panel.

In one embodiment, the circuitry comprises a processor and memorystoring programmatic instructions that, when executed, receives andprocesses a responsive signal generated by the second panel in responseto an electrical stimulation of the first panel.

In one embodiment, the circuitry comprises a processor and memorystoring programmatic instructions that, when executed, compares dataderived from said responsive signal to predetermined capacitance datafor liquids with known levels and known electrolyte compositions.

In one embodiment, the circuitry comprises a processor and memorystoring programmatic instructions that, when executed, determines afluid level and a composition of the electrolytes in said fluid based onthe data derived from the responsive signal and said predeterminedcapacitance data.

In one embodiment, the circuitry comprises a processor and memorystoring programmatic instructions that, when executed, receives dataindicative of a temperature from a temperature sensor, applies afunction of said data indicative of a temperature and data derived fromthe responsive signal to generate an output, compares said output todata derived from compositions of liquids having known levels ofelectrolytes and temperatures, and, based on said comparison, determinesa composition of said electrolytes in said fluid.

The present specification is also directed toward a dialysis system thatmonitors a level of a fluid and a composition of electrolytes in saidfluid, comprising: a dialysis machine for performing a dialysistreatment on a patient; a receptacle configured to receive a cylindricalcontainer, wherein said receptacle comprises a base from which extends apair of intertwined, mutually shielded conductive coils thatsubstantially encircle said container; and a circuit housed within thebase of the receptacle, wherein the circuit drives an inductive processto generate data indicative of a composition of said electrolytes in thefluid, generates data indicating the level of the fluid, and transmitssaid data indicative of the composition of said electrolytes and dataindicating the level of the fluid level to the dialysis machine.

The present specification is also directed toward a dialysis system thatmonitors a level of a fluid and a composition of electrolytes in saidfluid, comprising: a dialysis machine for performing a dialysistreatment on a patient; a receptacle configured to receive a cylindricalcontainer, wherein said receptacle comprises a base from which extends asingle shielded conductive coil that substantially encircles saidcontainer; and a circuit housed within the base of the receptacle,wherein the circuit drives an inductive process to generate dataindicative of a composition of said electrolytes in the fluid, generatesdata indicating the level of the fluid, and transmits said dataindicative of the composition of said electrolytes and data indicatingthe level of the fluid level to the dialysis machine.

The aforementioned and other embodiments of the present invention shallbe described in greater depth in the drawings and detailed descriptionprovided below.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will befurther appreciated, as they become better understood by reference tothe detailed description when considered in connection with theaccompanying drawings:

FIG. 1 is a side view illustration of one embodiment of the receptacleof the present specification, depicting the electrolyte containertherein;

FIG. 2 is an oblique top view illustration of one embodiment of theinside of the receptacle of the present specification;

FIG. 3 is a top down view illustration of one embodiment of thereceptacle of the present specification, depicting the electrolytecontainer therein;

FIG. 4 is an exemplary line graph depicting the volume of a number ofelectrolytes within a solution over time as measured using a capacitancemethod in accordance with one embodiment of the present specification;and,

FIG. 5 is an exemplary line graph depicting the volume of a number ofelectrolytes within a solution over time as measured using an ultrasonicmethod in accordance with one embodiment of the present specification.

DETAILED DESCRIPTION

The present invention is directed toward multiple embodiments. Thefollowing disclosure is provided in order to enable a person havingordinary skill in the art to practice the invention. Language used inthis specification should not be interpreted as a general disavowal ofany one specific embodiment or used to limit the claims beyond themeaning of the terms used therein. The general principles defined hereinmay be applied to other embodiments and applications without departingfrom the spirit and scope of the invention. Also, the terminology andphraseology used is for the purpose of describing exemplary embodimentsand should not be considered limiting. Thus, the present invention is tobe accorded the widest scope encompassing numerous alternatives,modifications and equivalents consistent with the principles andfeatures disclosed. For purpose of clarity, details relating totechnical material that is known in the technical fields related to theinvention have not been described in detail so as not to unnecessarilyobscure the present invention.

The present specification is directed toward methods and systems ofmonitoring the level and composition of electrolytes in fluid used indialysis treatment procedures. In one embodiment, the system utilizesactive capacitance to determine electrolyte level and composition.Included in the system is a receptacle attached to or positionedproximate a dialysis machine and adapted to receive a container that isused to house electrolytes in a fluid. In one embodiment, the receptacleincludes a base and at least two side panels configured to contact theexternal surface of the container when the container is placed withinthe receptacle. In one embodiment, the receptacle includes four sidepanels. In various embodiments, the receptacle includes less than ormore than four side panels, provided there are preferably an even numberof panels. The panels are made of any insulating material that is rigidenough to support the container. In one embodiment, the panels arecomposed of plastic.

In one embodiment, the panels are arranged in a circular pattern andtheir inside surfaces are shaped to match the curvature of thecontainer, thereby insuring a tight fit and maximizing contact betweenthe inner surface of each panel and external surface of the container.In one embodiment, the curvature of the inside surface of each panel isbetween 2 and 5 degrees concave, or curving inward to each panel andaway from the center of the container. The outside surface of each panelcan take any shape and, in one embodiment, is flat to ease handling. Theinside surface of each panel is covered with a conductive material foruse in the capacitance measurements. The conductive material extendsbeyond the lower edge of the panel and is in electrical contact with acircuit board housed in the base of the receptacle. In one embodiment,the conductive material is copper. The outer surface of each panel iscovered in a material for shielding. In one embodiment, the shieldingmaterial is copper. The panels are electrically isolated from oneanother but are in physical contact to insure a tight fitting with thecontainer. In various embodiments, the panels are attached at theirsides, tops, and/or bottoms. The receptacle also includes a base, towhich each individual panel is attached and on top of which rests thecontainer. In one embodiment, the panels are screwed into the base.

It should be appreciated that, while a circular pattern has beendisclosed, the panels may be positioned in rectangular, square,triangular or other polygonal shaped pattern, provided their insidesurfaces are shaped to match the external surface of the container,thereby insuring a tight fit and maximizing contact between the innersurface of each panel and external surface of the container, providedthe inner surface of each panel is covered with a conductive material,and provided each panel is electrically isolated from one another.

The receptacle includes a circuit board for driving the capacitiveprocess. The circuit board drives capacitance operations to generate andinterpret data concerning the level and composition of the electrolytesin the container. In one embodiment, the circuit board is housed in thebase. In another embodiment, the circuit board is isolated into a smallhousing and placed on an external surface of the reservoir andelectrically coupled to the receptacle via a wired or wireless contact.In another embodiment, the circuit board is isolated from thereceptacle, placed within the dialysis machine, and electrically coupledto the receptacle via a wired or wireless contact. In the embodimentswhere the circuit board is separate from the receptacle, the receptaclebase is a simple physical platform and is detachable from the panels topermit cleaning.

The container can be of any clarity or opacity, and need not betransparent. The outside curvature of the container is shaped to matchthe curvature of the inside surface of the panels. The height of thecontainer is designed to extend just above the top of the panels. Invarious embodiments, the container is composed of any non-metallicmaterial, such as glass or plastic.

The receptacle acts as a capacitor and is used to measure the level andcomposition of a fluid within the container. The capacitance of a pairof parallel plates varies with the spacing and with the dielectricconstant of the material which separates the plates of the capacitor.The dielectric is positioned between the two conducting plates, eachhaving an area A and a separation between the plates of d.

The simplest capacitor consists of two parallel conductive platesseparated by a dielectric with permittivity ε (such as air). The platesare considered to extend uniformly over an area A and a chargedensity±ρ=±Q/A exists on their surface. Assuming that the width of eachplate is much greater than their separation d, the electric field nearthe center of the device will be uniform with the magnitude E=ρ/ε. Thevoltage is defined as the line integral of the electric field betweenthe plates:

${V = {{\int_{0}^{d}{Edz}} = {{\int_{0}^{d}{\frac{\rho}{ɛ}{dz}}} = {\frac{\rho\; d}{ɛ} = {\frac{Qd}{ɛ\; A}.}}}}}\ $

Solving this for C=Q/V reveals that capacitance increases with area anddecreases with separation:

$C = {\frac{ɛ\; A}{d}.}$

Referring to the receptacle of the present specification, the panel areaand spacing are fixed. The dielectric constant of the water withelectrolytes in solution is much greater than that of air. In oneembodiment, the circuit board includes a resistor-capacitor (RC)oscillator. By placing the container with electrolytes in the circuit ofan RC oscillator, the frequency of the oscillator becomes a function ofthe fluid level in the container. The relationship between oscillatorfrequency and the partial volume of electrolyte as a percentage of thetotal volume is slightly non-linear. The curve fit to correct for thenon-linearity is a simple second order polynomial.

The plates of the capacitor are formed by the electrodes surrounding thecontainer. In one embodiment, grounded shield electrodes are included tominimize the effects of other objects in the vicinity outside of thecontainer. When the container is empty, the frequency of the oscillatoris at a maximum. This frequency is in effect set by the combination of a5 picofarad (pF) capacitor and the stray capacitance in response to thephysical layout.

In one embodiment, a second oscillator with a 5 pF capacitor is includedbut has no connection to the container. This oscillator is used to trackthe effects of temperature on the fluid within the container.

In one embodiment, the receptacle includes an I2C peripheral comprisingan impedance bridge. The impedance bridge measures the dissipationfactor of the contents of the container to enable the receptacle todistinguish between water and water with electrolytes dissolved in it.

In one embodiment, the receptacle includes a small serial flash memoryfor storage of the last calibration values. This will enable thereceptacle to have more accurate results after a mid-procedure restart.

During operation, a programmable processor on the circuit boardgenerates alternating current (AC) excitation in the form of astimulation waveform and transmits it to the conductive material coveredinside surface of at least one of the side panels. The circuit boardthen receives, and measures, a responsive waveform indicative of theelectrically coupled response from the conductive material coveredinside surface of the opposing side panel. The measured capacitance willchange depending on the volume and composition of the electrolytes inthe container. Measured values are then compared with previouslycalculated capacitance values of known liquids and volumes to determinethe electrolyte level and composition.

In one embodiment, the system is calibrated before providing a containerwith an electrolyte solution. During calibration, the receptaclemeasures the capacitance of an empty and present container. The emptycontainer capacitance is set at zero, effectively taring the system. Thesystem is further calibrated by providing an AC excitation and measuringthe coupled response for a set of liquids whose volume and electrolytelevel are known. Preferably, the calibration is a one-time manufacturingprocess and performed in a closed environment using a crystal oscillatorto measure capacitance.

In one embodiment, the processor is programmed to provide AC excitationand record capacitance measurements, in a local memory, at predeterminedintervals. In one embodiment, the predetermined interval is every onesecond. In one embodiment, the system operates at 3.3 V and isconfigured to differentiate between pure water and electrolyte solutionscontaining differing concentrations of potassium, magnesium, and/orcalcium.

The present specification is also directed toward a method and system ofmonitoring the level and composition of electrolyte used in dialysistreatment procedures through the use of induction measurements. In oneembodiment, the system comprises a base and a receptacle having a pairof intertwined, mutually shielded conductive coils that wrap around acontainer with electrolyte. Mutual inductance is measured between thetwo coils on opposing sides of the container to determine liquid level.Temperature measurements can be combined with the inductance measurementto determine liquid composition. In one embodiment, the device isfactory calibrated using known liquids and levels.

In another embodiment, the system utilizing inductance comprises a baseand a receptacle having a single conductive coil that wraps around acontainer with electrolyte. Single inductance is measured between thecoil on side of the container and the coil on the opposite side of thecontainer to determine liquid level. Temperature measurements can becombined with the inductance measurement to determine liquidcomposition. In one embodiment, the device is factory calibrated usingknown liquids and levels.

The present specification is also directed toward a method and system ofmonitoring the level and composition of electrolyte used in dialysistreatment procedures through the use of ultrasonic measurements. Theultrasonic measurements are taken and interpreted using methods andsystems similar to those described in U.S. Pat. No. 7,661,294, entitled“Non-invasive multi-function sensor system” and assigned to theapplicant of the present invention and to Measurement Specialties, Inc.,which is herein incorporated by reference in its entirety.

Referring to FIG. 1 , a side view illustration of one embodiment of thereceptacle 100, depicting the electrolyte container 150, is shown. Thereceptacle 100 comprises a plurality of side panels 110 which, whenassembled with the receptacle base 120, form a cavity for receiving thecontainer 150. The side panels 110 preferably have an internal surfacethat is curved to match the curvature of the container 150. The entirepanel 110, however, need not be curved with the outside being able tohave a variety of different curved, straight, or angular surfaces.

The outer surface of each panel 110 is covered by a shielding material112. The inside surface of each panel 110 is covered by a metallicmaterial (as seen in FIG. 2 ) for use in the capacitive process. Eachpanel 110 is electrically isolated from the other panels 110. Neitherthe shielding material 112 nor the metallic material extends onto theside surfaces 114 of adjacent panels 110. In one embodiment, extendingfrom both side surfaces 114 of each panel is a fin 115. Two opposingfins 115 come into physical contact at the base 120 of the receptacle.The fins 115 recede toward the side surface 114 as they extend up alongthe side of each panel such that they are flush with the side surface114 once they reach the top edge of the panel 110. The fins 115 are notcovered by any conductive elements so that the panels remainelectrically isolated. The physical alignment of the fins 115 at thebase 120 act to create a more secure fit for the container 150.

In the pictured embodiment, the electronics 130 of the receptacle 100are housed in the base 120. In one embodiment, the conductive materialon the inside surface of each panel 110 extends beyond the bottom edgeof the panel and is electrically connected to the electronics 130 in thebase 120. This allows for the generation of a stimulation waveform fromthe electronics 130 and through the conductive material for thecapacitance measurement. In another embodiment, the electronics are nothoused in the base and conductive wires extend from the bottom of eachpanel 110 through a distance, which may include into the dialysismachine itself, to electrically connect the conductive material with theelectronics.

The panels may be fixedly or removably attachable to the base. Forexample, the panels may be permanently welded, molded, or glued into oronto the top surface of the base. The panels may also be removablyattached into or onto the top surface of the base by having the panelspositioned in slots in the base surface, attached by latches, hooks, orother attachment means.

FIG. 2 is an oblique top view illustration of one embodiment of theinside of the receptacle 200. The electrolyte container has been removedto assist in visualization. The inside surface of each panel 210 iscovered with a metallic material 213 for use in the inductive process.The bottom portions of opposing fins 215 meet at the base 220 toincrease stability. Once again, in the pictured embodiment, theelectronics 230 of the receptacle 200 are housed in the base 220.

FIG. 3 is a top down view illustration of one embodiment of thereceptacle 300, depicting the electrolyte container 350 therein. In thepictured embodiment, the receptacle 300 comprises four panels 310 and abase 320. Each panel 310 includes a shielding cover 312 on its outersurface, a metallic material 313 on its inner surface, a side surface314 on each lateral side of each panel 310 and a tapering fin 315, whichtapers toward the top and is thickest at the bottom, extending from eachlateral side surface 314. The shielding cover 312 and metallic material313 do not extend over the side surfaces 314 or fins 315, therebykeeping the panels 310 electrically isolated from one another. The base320 includes the electronics 330 that generate the stimulation wave,receive the responsive wave, store calibration data, and calculate fluidlevels and electrolyte compositions based on the responsive wave andstored calibration data.

FIG. 4 is an exemplary line graph depicting the volume of water and anumber of electrolytes within a solution over time as measured using acapacitance method in accordance with one embodiment of the presentspecification. The graph illustrates the levels of water 405, K2 410, K3415, NaCl(60) 420, and KCl+(1 mol) 425 over time at a dialysis flow rateof approximately 36 ml/min. The volumes of water and the electrolytescan be seen decreasing over time as the solution is used by the dialysissystem. Such a graph can be compared to known values of water andelectrolytes processed at the same rate to determine current solutionlevel and composition.

FIG. 5 is an exemplary line graph depicting the volume of water and anumber of electrolytes within a solution over time as measured using anultrasonic method in accordance with one embodiment of the presentspecification. The graph illustrates the levels of water 505, Na₂CO₃510, Low K 515, K1+Ca0.5 520, K1 525, K1+(1 mol) 530, K2 535, and K3 540over time at a dialysis flow rate of approximately 1 ml/min for 1 hour.The graph also includes a linear measure line 550 for reference. Thevolumes of water and the electrolytes can be seen decreasing over timeas the solution is used by the dialysis system. Such a graph can becompared to known values of water and electrolytes processed at the samerate to determine current solution level and composition. When comparedto the graph of FIG. 4 , the values decrease in a more linear fashion.

The above examples are merely illustrative of the many applications ofthe system of the present invention. Although only a few embodiments ofthe present invention have been described herein, it should beunderstood that the present invention might be embodied in many otherspecific forms without departing from the spirit or scope of theinvention. Therefore, the present examples and embodiments are to beconsidered as illustrative and not restrictive, and the invention may bemodified within the scope of the appended claims.

We claim:
 1. A dialysis system configured to monitor a composition ofelectrolytes in a fluid located within a contained volume, the dialysissystem comprising: a first surface positioned external to, and proximateto, the contained volume, wherein the first surface comprises aconductive material; a second surface positioned external to, andproximate to, the contained volume; and a circuit in electrical contactwith the conductive material, wherein the circuit comprises a processorand a memory storing programmatic instructions that, when executed:generates a stimulation wave; transmits the stimulation wave to thefirst surface; receives a responsive signal generated by the secondsurface; determines capacitance data from the responsive signal;compares the capacitance data to predetermined capacitance data, whereinthe predetermined capacitance data relates capacitance values to knownelectrolyte compositions; and determines a composition of electrolytesin the fluid based on the capacitance data and the predeterminedcapacitance data.
 2. The dialysis system of claim 1, wherein the firstsurface is electrically isolated from the second surface.
 3. Thedialysis system of claim 1, wherein the first surface and the secondsurface each have a convex shaped surface.
 4. The dialysis system ofclaim 1, wherein the dialysis system is further configured to monitor alevel of the fluid in the contained volume.
 5. The dialysis system ofclaim 4, wherein the predetermined capacitance data relates capacitancevalues to fluid levels.
 6. The dialysis system of claim 5, wherein thecircuit is further configured to determines the level of the fluid basedon the data derived from the responsive signal and the predeterminedcapacitance data.
 7. The dialysis system of claim 1, wherein the firstsurface is in a first panel, wherein the second surface is in a secondpanel, and wherein the first panel opposes the second panel.
 8. Thedialysis system of claim 1, wherein the first surface and the secondsurface are attached to a common base.
 9. The dialysis system of claim8, wherein the circuit is positioned within the common base.
 10. Thedialysis system of claim 1, wherein the first surface comprises a firstconductive coil.
 11. The dialysis system of claim 1, wherein the secondsurface comprises a second conductive coil.
 12. The dialysis system ofclaim 1, further comprising a temperature sensor, wherein the circuit isin electrical contact with the temperature sensor.
 13. The dialysissystem of claim 12, wherein the circuit is configured to receive dataindicative of a temperature from the temperature sensor and determinethe composition of the electrolytes in the fluid based, in part, on dataindicative of the temperature.
 14. The dialysis system of claim 1,wherein the circuit further comprises an impedance bridge adapted tomeasure a dissipation factor related to the fluid in the containedvolume.
 15. The dialysis system of claim 14, wherein the circuit isconfigured to distinguish between the fluid without the electrolytes andthe fluid with the electrolytes based on the dissipation factor.
 16. Thedialysis system of claim 1, wherein the circuit comprises an oscillatorand wherein a frequency of the oscillator is a function of a level ofthe fluid in the contained volume.
 17. The dialysis system of claim 1,wherein the first surface is in a first panel, wherein the secondsurface is in a second panel, and wherein each of the first surface andthe second surface is shaped to match a curvature of an external surfaceof the contained volume.
 18. The dialysis system of claim 17, whereineach of the first panel and the second panel is removably attached to aslot positioned within common base.
 19. The dialysis system of claim 1,wherein at least one of the first surface or the second surface isdefined by a curvature in a range of 2 to 5 degrees.
 20. A dialysissystem configured to monitor a composition of electrolytes in a fluidlocated within a contained volume, the dialysis system comprising: afirst surface positioned external to, and proximate to, the containedvolume, wherein the first surface comprises a conductive material; asecond surface positioned external to, and proximate to, the containedvolume, wherein the second surface comprises the conductive material andwherein the first surface and the second surface are electricallyisolated from each other; and a circuit in electrical contact with theconductive material, wherein the circuit comprises a processor and amemory storing programmatic instructions that, when executed: generatesa stimulation wave; transmits the stimulation wave to the first surface;receives a responsive signal generated by the second surface; determinescapacitance data from the responsive signal; compares the capacitancedata to predetermined capacitance data, wherein the predeterminedcapacitance data relates capacitance values to known electrolytecompositions; and determines a composition of electrolytes in the fluidbased on the capacitance data and the predetermined capacitance data.